Cinema, as Jean-Luc Godard wrote, is truth 24 times a second. Documentaries both prove and disprove the point; but the truth is their strongest weapon. Here, Guardian and Observer critics pick the 10 best

Claude Lanzmann's new film focuses on a figure too complex and controversial for his seminal Holocaust documentary, Shoah – the Jewish Council president who collaborated with the Nazis. Agnès Poirier talks to the director about coming to admire a pariah

Claude Lanzmann's mesmerising nine-and-a-half-hour movie Shoah forced audiences to reimagine the Holocaust. Now he's turned his attention to the 600 Jews who overthrew a Nazi death camp. The Parisian director talks to Peter Lennon.